What about our good works? Saving faith, after all, must produce good works. Do those good works justify us? Are they part of the basis upon which God pardons us and accepts and accounts us righteous? Not at all. Those good works simply evidence that faith is genuine (see James 2:14-26). We must never rely upon our good works as even the smallest part of the basis of our Justification. Justification is based entirely on what Christ has done, and all glory goes to our great God. (24, Bold added)
Justification, therefore, is not a change that God makes within us (although every justified believer is also and of necessity sanctified). The basis of that declaration is not what God already sees in us, nor what God does in us, nor even what God foresees that we will do or he will do in us. Nor does God accept faith instead of good works as the basis of our acceptance. The sole basis of that declaration is without, or outside, ourselves. That basis is the perfect obedience and full satisfaction of Jesus Christ (WLC 70). (23-24)
From the book By Faith Alone: Answering the Challenges of the Doctrine of Justification Edited by Gary L. W. Johnson & Guy P. Waters.